title: Recombinant protein YbgF induces protective immunity against Rickettsia heilongjiangensis infection in C3H/HeN mice.
abstract: BACKGROUND
  Surface proteins YbgF and PrsA are major seroreactive antigens of Rickettsia heilongjiangensis, the etiological agent of Far-Eastern spotted fever. This study investigated their potential immunogenicity for protective immunity.
  
  
  METHODS
  Recombinant YbgF and PrsA were used to immunize C3H/HeN mice and rickettsial loads in immunized mouse organs were assessed after R. heilongjiangensis challenge. Anti-sera from immunized mice were applied to neutralize rickettsiae. CD4⁺ and CD8⁺ T cells isolated from R. heilongjiangensis-infected mice were stimulated with YbgF or PrsA, and proliferation and cytokine production assessed.
  
  
  RESULTS
  The IgG2a/IgG1 ratio of sera was markedly increased in YbgF-immunized mice but was unaltered in PrsA-immunized mice after immunization. The rickettsial load in YbgF-immunized mice was significantly lower than in PrsA-immunized mice after R. heilongjiangensis challenge. Incubation with anti-serum to YbgF, but not PrsA, significantly reduced the number of rickettsiae adhering to and invading endothelial cells. The proliferation level and tumor necrosis factor-α secretion level of CD4⁺ T cells from R. heilongjiangensis-infected mice were significantly higher than in uninfected mice after stimulation with YbgF but not PrsA.
  
  
  CONCLUSIONS
  YbgF is a novel protective antigen that induces a Th1-type of protective immune response against R. heilongjiangensis infection.
authors.affiliation: State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, 20 Dong-Dia-Jie Street, Fengtai, Beijing 100071, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Qi
authors.forename: Xiaolu
authors.initials: X
authors.lastname: Xiong
authors.forename: Changsong
authors.initials: C
authors.lastname: Duan
authors.forename: Jun
authors.initials: J
authors.lastname: Jiao
authors.forename: Wenping
authors.initials: W
authors.lastname: Gong
authors.forename: Bohai
authors.initials: B
authors.lastname: Wen
mesh_terms: D000825:Animal Structures / Q000382:microbiology; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D057134:Antibodies, Neutralizing / Q000097:blood; D000942:Antigens, Bacterial / Q000235:genetics / Q000276:immunology*; D058491:Bacterial Load; D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology*; D001428:Bacterial Vaccines / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D049109:Cell Proliferation; D016207:Cytokines / Q000378:metabolism; D004195:Disease Models, Animal; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000276:immunology*; D051379:Mice; D008809:Mice, Inbred C3H; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology; D012281:Rickettsia / Q000235:genetics / Q000276:immunology*; D012282:Rickettsia Infections / Q000517:prevention & control*; D018417:Th1 Cells / Q000276:immunology; D022223:Vaccines, Subunit / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology; D014614:Vaccines, Synthetic / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology
chemical_list: D000907:Antibodies, Bacterial; D057134:Antibodies, Neutralizing; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D001428:Bacterial Vaccines; D016207:Cytokines; D008565:Membrane Proteins; D011994:Recombinant Proteins; D022223:Vaccines, Subunit; D014614:Vaccines, Synthetic
keywords: Far-Eastern spotted fever; OD(450); Protective antigen; Rickettsia heilongjiangensis; Serum neutralization; Surface protein; Th1-type immune response; WCA; optical density at 450nm; rPrsA; rYbgF; recombinant PrsA; recombinant YbgF; whole cell antigens